(RHSA-2010:0627) Important: kvm security and bug fix update

KVM (Kernel-based Virtual Machine) is a full virtualization solution for
Linux on AMD64 and Intel 64 systems. KVM is a Linux kernel module built for
the standard Red Hat Enterprise Linux kernel.

It was found that QEMU-KVM on the host did not validate all pointers
provided from a guest system’s QXL graphics card driver. A privileged guest
user could use this flaw to cause the host to dereference an invalid
pointer, causing the guest to crash (denial of service) or, possibly,
resulting in the privileged guest user escalating their privileges on the
host. (CVE-2010-0431)

A flaw was found in QEMU-KVM, allowing the guest some control over the
index used to access the callback array during sub-page MMIO
initialization. A privileged guest user could use this flaw to crash the
guest (denial of service) or, possibly, escalate their privileges on the
host. (CVE-2010-2784)

A NULL pointer dereference flaw was found when the host system had a
processor with the Intel VT-x extension enabled. A privileged guest user
could use this flaw to trick the host into emulating a certain instruction,
which could crash the host (denial of service). (CVE-2010-0435)

This update also fixes the following bugs:

• running a “qemu-img” check on a faulty virtual machine image ended with a
  segmentation fault. With this update, the segmentation fault no longer
  occurs when running the “qemu-img” check. (BZ#610342)

• when attempting to transfer a file between two guests that were joined in
  the same virtual LAN (VLAN), the receiving guest unexpectedly quit. With
  this update, the transfer completes successfully. (BZ#610343)

• installation of a system was occasionally failing in KVM. This was caused
  by KVM using wrong permissions for large guest pages. With this update, the
  installation completes successfully. (BZ#616796)

• previously, the migration process would fail for a virtual machine
  because the virtual machine could not map all the memory. This was caused
  by a conflict that was initiated when a virtual machine was initially run
  and then migrated right away. With this update, the conflict no longer
  occurs and the migration process no longer fails. (BZ#618205)

• using a thinly provisioned VirtIO disk on iSCSI storage and performing a
  “qemu-img” check during an “e_no_space” event returned cluster errors. With
  this update, the errors no longer appear. (BZ#618206)

All KVM users should upgrade to these updated packages, which contain
backported patches to resolve these issues. Note: The procedure in the
Solution section must be performed before this update will take effect.